geometrical shapes
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Crystals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 65
Author(s):  
Niloofar Esmaeildoost ◽  
Olof Jönsson ◽  
Trevor A. McQueen ◽  
Marjorie Ladd-Parada ◽  
Hartawan Laksmono ◽  
...  

Understanding how ice nucleates and grows into larger crystals is of crucial importance for many research fields. The purpose of this study was to shed light on the phase and structure of ice once a nucleus is formed inside a metastable water droplet. Wide-angle X-ray scattering (WAXS) was performed on micron-sized droplets evaporatively cooled to temperatures where homogeneous nucleation occurs. We found that for our weak hits ice grows more cubic compared to the strong hits that are completely hexagonal. Due to efficient heat removal caused by evaporation, we propose that the cubicity of ice at the vicinity of the droplet’s surface is higher than for ice formed within the bulk of the droplet. Moreover, the Bragg peaks were classified based on their geometrical shapes and positions in reciprocal space, which showed that ice grows heterogeneously with a significant population of peaks indicative of truncation rods and crystal defects. Frequent occurrences of the (100) reflection with extended in-planar structure suggested that large planar ice crystals form at the droplet surface, then fracture into smaller domains to accommodate to the curvature of the droplets. Planar faulting due to misaligned domains would explain the increased cubicity close to the droplet surface.


2021 ◽  
pp. 1-11
Author(s):  
Mehrad Gavahi ◽  
Hong Rong Li

In this work, a model of optomechanical system was investigated by analyzing the entanglement dynamics of two related mechanical oscillators in a modified system. Geometrical shapes effects of optical cavities on entanglement of a representative optomechanical system were investigated by means of performing numerical analysis. It was signified that the steady-state or the dynamic behavior of optomechanical engagement could be created owing to the strength of mechanical pairs, which are strong towards the oscillating temperature. In addition, the mentioned entanglement dynamics were seen to be entirely related to the natural state’s stability. Furthermore, rendering the mechanical damping effects, the critical mechanical coupling strength-related analytical expression, where the transition from a steady state to a dynamic clamp occurs, was reported. In the studied system, two identical mechanical oscillators were formed in different conditions of the optical cavities shapes.


2021 ◽  
Author(s):  
Khosrow Hosseini ◽  
Shahab Nayyer ◽  
Mehran Kheirkhahan ◽  
Sayed-Farhad Mousavi

Abstract Modifying the river course for flood control, prevention of bed erosion, bank protection, and the regulation of river width are among the goals of spur dikes incorporation. The common spur dikes have simple (I), L and T geometrical shapes. The present research has been conducted to reduce the scour depth in front of the spurs dikes and improve the sedimentation conditions for the LTT combination of spur dikes in series by investigating different combinations of slots in the body of the spur dike; using numerical methods. The slot dimension was taken equal to 10% of the effective area of the spur dike body. Finally, the (LS-W-Wi, TS-W, TS-W-Wi) combination contained the slots in the web and wing of the first and third spur dike also the slot at the web of the middle spur dike was found as the best combination of slots. This combination conducted to reduce the scour depth about 6.8% and increase the deposition about 52% comparing by the spurs dikes without slots. Reducing the scour depth and increasing the sedimentation rate of materials between the spurs dikes. Also, the maximum scour depth decreases up to 20%. The results revealed that the presence of slots in spur dike structures and their different positions have complicated and considerable influences on the form and morphology of the erodible bed which could be the topic for further researches.


Plasmonics ◽  
2021 ◽  
Author(s):  
Hassan Sayed ◽  
Sagr Alamri ◽  
Zeinab Matar ◽  
Arafa H. Aly

2021 ◽  
Vol 11 (17) ◽  
pp. 8115
Author(s):  
Radu Mihalache ◽  
Dragos Mihai ◽  
Gheorghe Megherelu ◽  
Ionut Florian Popa ◽  
Ionut Sebastian Vintila ◽  
...  

The mission objective of the Phobos Sample Return is to collect and return 100 g of Phobos’ surface material to Earth inside a tight enclosure composed of a Vault, a Sample Container and sealing elements. One important aspect of the project was the development of a closing mechanism capable of ensuring a pushing force high enough compared to the available force of the robotic arm (40 N). The need for a higher pushing force derived from the design tests which were carried out to experimentally determine the necessary force to overcome the resistance of the sealing element when the vault is closed. Two types of sealing elements, custom made for this project, along with two SC with different geometrical shapes in the sealing area were tested. For better accuracy, the tests considered the imposed operational temperature domain for the vault, ECSS standards and the test rig set-up being performed at environmental temperature (+20 °C), −20 °C, −60 °C and +70 °C. The results of the tests highlighted that the negative temperature has a significant influence over the closing force, as this force is increasing once the operational temperature is decreasing. Based on the work performed, the most suitable type of sealing element was identified, in particular the piston geometry which allows a smaller force to close the vault.


Author(s):  
Yashwant Koli ◽  
N Yuvaraj ◽  
Aravindan Sivanandam ◽  
Vipin

Nowadays, rapid prototyping is an emerging trend that is followed by industries and auto sector on a large scale which produces intricate geometrical shapes for industrial applications. The wire arc additive manufacturing (WAAM) technique produces large scale industrial products which having intricate geometrical shapes, which is fabricated by layer by layer metal deposition. In this paper, the CMT technique is used to fabricate single-walled WAAM samples. CMT has a high deposition rate, lower thermal heat input and high cladding efficiency characteristics. Humping is a common defect encountered in the WAAM method which not only deteriorates the bead geometry/weld aesthetics but also limits the positional capability in the process. Humping defect also plays a vital role in the reduction of hardness and tensile strength of the fabricated WAAM sample. The humping defect can be controlled by using low heat input parameters which ultimately improves the mechanical properties of WAAM samples. Two types of path planning directions namely uni-directional and bi-directional are adopted in this paper. Results show that the optimum WAAM sample can be achieved by adopting a bi-directional strategy and operating with lower heat input process parameters. This avoids both material wastage and humping defect of the fabricated samples.


2021 ◽  
Vol 12 ◽  
Author(s):  
Riccardo Brunetti ◽  
Allegra Indraccolo ◽  
Claudia Del Gatto ◽  
Benedetto Farina ◽  
Claudio Imperatori ◽  
...  

The Stroop effect is a well-documented phenomenon, demonstrating both interference and facilitation effects. Many versions of the Stroop task were created, according to the purposes of its applications, varying in numerous aspects. While many versions are developed to investigate the mechanisms of the effect itself, the Stroop effect is also considered a general measure of attention, inhibitory control, and executive functions. In this paper, we implement “eStroop”: a new digital version based on verbal responses, measuring the main processes involved in the traditional effect. eStroop features four categories of stimuli in four different colors: (1) geometrical shapes, (2) neutral words, (3) congruent words, and (4) incongruent words. The results of the administration to 307 University students confirm the Stroop effect and offer baseline data for future research and clinical testing. Direct comparisons with other recent versions of the task are discussed, offering insights into differences and similarities between different task variables.


Perception ◽  
2021 ◽  
Vol 50 (5) ◽  
pp. 387-398
Author(s):  
Ruth Hofrichter ◽  
Megan E. Mueller ◽  
M. D. Rutherford

Adults describe abstract shapes moving in a goal-directed manner using animate terms. This study tested which variables affect school-aged children’s descriptions of moving geometrical shapes. Children aged 5 to 9 years were shown displays of interacting geometrical shapes and were asked to describe them. Across participants, instructions, number of moving figures, whether a figure caught another, and complexity of the scene were manipulated. Nine-year-olds used significantly more animate phrases than 5-year-olds. Furthermore, we found an Age by Condition interaction. Five-year-olds made significantly more animate statements in the animate condition, while 7-year-olds and 9-year-olds were less affected by instructions. Scene complexity increased children’s use of animate phrases. Number of agents present on the screen and whether a catch occurred did not impact children’s animate attributions. Our results support the hypothesis that children, like adults, are attuned to animacy cues and describe chasing agents in animate terms.


Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 583
Author(s):  
Chin-Feng Lee ◽  
Jau-Ji Shen ◽  
Somya Agrawal ◽  
Yen-Hsi Li

Data hiding is a technique that embeds a secret message into a cover medium and transfers the hidden information in the secret message to the recipient. In the past, several data hiding methods based on magic matrix have used various geometrical shapes to transmit secret data. The embedding capacity achieved in these methods was often limited due to simple geometrical layouts. This paper proposes a data hiding scheme based on a double-layer octagon-shaped shell matrix. Compared to previous octagon-shaped data hiding methods, the proposed method embeds a total of 7 bits in each pixel pair, reaching an embedding capacity of 3.5 bits per pixel (bpp). Experimental results show that the proposed scheme has a higher embedding capacity compared to other irreversible data hiding schemes. Using the proposed method, it is possible to maintain the Peak Signal to Noise Ratio (PSNR) within an acceptable range with the embedding time less than 2 s.


2021 ◽  
Vol 7 ◽  
Author(s):  
Iakov A. Lyashenko ◽  
Qiang Li ◽  
Valentin L. Popov

We investigate experimentally and numerically the influence of chemical heterogeneity and of third-body particles on adhesive contact. Chemical heterogeneity is generated by chemical treatment of the contacting bodies changing locally the surface energy. For studying the influence of the third body, two types of particles are used: sand particles with various geometrical shapes and sizes, and steel spheres of equal radius. Dependencies of the normal force on the indentation depth at both indenting and pull-off as well as the evolution of the contact configuration are investigated. Corresponding numerical simulations are carried out using the boundary element method (BEM).


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